Within the mirror housing of the inside rear-view mirror of a car, the control mechanism for switching the mirror glass from a full reflectance position to a partial reflectance position includes a set motor and various other heavy components. Moreover, the mirror housing is additionally equipped with indicators (West German Published Patent Application No. 32 34 157), the displays and associated electronic control of which add to the weight of the completely equipped mirror housing. Usually, the mirror housing is pivotably supported by a free end of an arm which projects into the interior of the car and the base of which is releasably mounted on a supporting plate provided on an upper portion of the car body or on the inner surface of the windshield (West German Published Patent Application No. 29 47 512).
It is a drawback of such inside rear-view mirrors that vibrations of the car body caused by the running engine are transmitted to the mirror arm and lead to corresponding vibrations of the mirror glass within the mirror housing. Due to the increased weight of the mirror housing, the characteristic frequency of the inside rear-view mirror is shifted to a lower frequency, which causes vibrations of increasing amplitudes. This not only reduces the safety and reliability of the mounting of the inside rear-view mirror, but also substantially obscures a clear and steady rear view seen in the mirror.